Process for treating manganese-silver ores



Nov. 24 1925.

M. F. COOLBAUGH ET AL PROCESS FOR TEEATING MANGANESE SILVER oEEs Filed March 4 5: f r f f mwa/m5@ RSN O lltatentted lltlov. Wl, i925.

P A T E F'ICE'..

lttldlLVltLLlEl 3F. COOLBAUGI'I AND JOHN BURNS READ. Oft? GOLDEN, COLRADD, AEESGNORS '130 THE CMPLEX GRES RECQVERIES CMPANY, 0F DENVER, CLRADD, A COR EPURATION DF COLORADD.

PROCESS FOR TRETINGl MANGANESE-ILVER CRES.

Application filed Merch 4, 192.2. Serial No. 541,079.

fo u?? whom 1'/ may concern.'

lle it known that We, Mnnvlnnn F. Cool.- nwon and .loIIN BnuNs Rican, citizens oi. the United States, and residents ot Golden, in the eountv olI Jefferson, State ol." Colorado` have invented certain new and use'tul lmproif'enxents in Processes 'for Treatlngj, Manganeselilver Orcs: and we do declare the following' to he a full, clear, and exact description of the invention, such as will enable others skilled in the art: to which it. appertains to malte and use the saine, relerence bennan had to the aceonu'mnying d a\vin gs, which :form a partI of this s})ee1lication.

The object o'l this invention prin'larily is to recover silver vfrom manganesesilver ores. this obiect beine' attained by so treating); the ores that lthe silver is rendered amenable to yrecovery hy known methods. As the process is carried out, the recovery ol the manganese also. becomes a. secondary object.

lleretolore the recovery of silverv l'rom man- ;anesesilver ores by cyanidation has been decidedly dilticult, very low extractions having been obtained by direct treatnlent. i, however, the manganese is reduced, and especially it it is rendered soluble and separated troni the silver, the silver then is elliciently dissolved by the cyanide. Many methodshave been proposed both for the reduction and the solution ot the manganeso and some very hin-h recoveries of silver 'from the residues have been elleeted. For low grade ores, however. the costs ot such methods have gent-rally been prohibitive.

lite have discovered that manganeso in maunaneue-silver ores can be. reduced or changed to sulfate, which is soluble in water, h v roasting' the oro with pyrite or with other sultides or with elemental sulfur. For an ellcieut change to sulfate it is necessary that the ore and sulfur mineral together with the air tor roastingand the products of the roast travel together in the salue direction throughout the entire treatment.

'lhe manganese ores to which this method ot treatment. will applyA are more partiieul arly oxides and especially the higher oxides, but rarhonates and silicates are also susceptible to the treatn'lent to render the manu danese soluble. Throughout this specifica tion and the claims, theterm ore is intil tended to include concentrates, tailings and other metalli'ferous matter as well as raw ores.

The process may be carried out in any suitable type of furnace. ln the accom* panying' drawings one type ot roasting furnace is indicated diae'l'aunnatically, the steps and reactions ot the process being also in' dicated.

lt the reduction ot the manganese alone is desired, the manganese mineral with the sultide or sulfur are charged into the 'turnace together and only a limited amount of air introduced. The sulfur 'reacts With the oxygen ot the higher oxides causing a reduction which is illustrated by the follow ini,r equation:

'lhe mengen' se remains as an insoluble co1npound with the. residue, and the silver is in a. condition tor extraction With cyanide.

lln order to torni soluble manganese, it is necessary that the ore mixed with the sulfide or sulfur mineral should travel in the same direction throughout the entire treatment with the air and gaseous products oi the roast. Under these circumstances an excess ot air is employed and the manganese is converted as completely as possible into' the sulfato. The calcine is treated with Water alone or with Water and sulpl'un'ic acid to remove any soluble sullates, and the residue is treated with cyanide Ylor the extraction ol silver. rlhe manganese or other soluble sulfatos may be recovered lrom the solution by cryatallization. The chemical changes which take place in the 'furnace and in the leaching; are in some respects similar to those set lorth in our cro-pending' application Serial No. 340,888 tiled November E26, 1919.

ln the lirstzone oi. the lfurl'lace the ore, the sulfide or sulfur mineral, and the air `for roasting are introduced. It the quantity el' sulfur is not suiiicient to give the heat required in the furnace, fuel or heat in some other form must be employed. In this zone the greatest desultidiziinr takes place, and some metallic oxides lorin. Sulfur dioxide lirst termed reacts with the excess et air present to form sulfur trioxde. The rate (iti llltl of this reaction is materially influenced by the presence of ferrie oxide (FegOS), manganese dioxide (MnOZ) and to a lesser eX- tent by other oxides. The sulfur trioxide formed may react with some of the metallic oxides to form sulfates. In this zone the temperature is maintained between 600 C. and 10000 C., depending somewhat upon the minerals in the ore being handled.

In the second or central zone of the furnace more sulfide is decomposed and more sulfur trioxide and some sulfates are formed.

In the third or final zone, small quantities of sulfides are still being decomposed and large quantities of sulfates are formed.

The temperature in thesecond zone may be about the same as that in the first zone. Such temperature will depend largely upon the minerals being treated. The temperature in the third zone is lower than that in the second zone, and in the case of formation of manganese sulfate should be below the decomposition point of this salt.

Silver is one of the metals which holds sulfide sulfur very tenaciously, and if other sulfide sulfur is not completely oxidized during the roast the silver remains as an insoluble sulfide. In this form it can be dissolved in cyanide. If the sulfur has been very completely oxidized, the silver will be in the form of sulfate which is soluble in water or sulfuric acid. Under these circumstances, if it is desired to keep the silver with the residue a small quantity of a soluble chloride or a soluble sulfide may be added to precipitate the silver, the silver being subsequently recovered from the residue by cyanide treatment.

The amount of sulfide or sulfur to be mixed with the manganese ore will vary with the manganese content. An amount of sulfur slightly in excess of that neeessar to react with the manganese to form sulfate, should be present. Thus, the retention of silver as sulfide may be insured.

We claim:

l.. A process of treating ores containing silver, manganese and sulfides, comprising treating the ores at a temperature and for such a length of time as will insure roasting of suldes other than silver sulfide and at the same time prevent a dead roast so as to insure retention of silver sulfide, advancing the minerals and liberated gases together in the same direction, and lowering the temperature below the decomposition temperature of manganese sulfate for the action of sulfur gases on the manganese mineral to form manganese sulfate.

2. A process of treating ores containing silver, manganese and sulfides, comprising treating the ores at one step at a temperature to roast certain sulfides and under conditions to retain silver sulde, advancing the ores and liberated gases together in the same direction, and lowering the temerature for the action of sulfur gases on the manganese mineral to form manganese sulfate.

3. A process of treating silver-manganese ores containing sulfides, comprising treat-` ing the ores at a temerature high enough to roast sulfides other than silver sulfide and at least as high as'the decomposition temperature of manganese sulfate, and under conditions to prevent decomposition of silver sulfide, advancing the ores and liberated gases together in the same directiomand lowering the temperature for the action of sulfur gases on the manganese mineral to form manganese sulfate.

l. A process of treating orcs containing silver, n'ianganese and sulfides, comprising treating the ores ata temperature to roast sulfides other than silver sulfide and at least as high as the decomposition ten'iperature of manganese sulfate and in an atmosphere containing sulfur sufficient to prevent decomposition of silver sulfide, advancing the ores and liberated gases together in the same direction, and lowering the temperature for the action of sulfur gases on the manganese mineral to form manganese sulfate.

5. A process of treating silver-manganese ores containing sulfur comprising roasting the ores and liberating sulfur gases, treating the roasted ores with said gases and forming manganese sulfate thereby, and removing the manganese sulfate from the residue with a solvent.

6. The method of treating a manganese silver ore which comprises passing ore sulphur-containing material and air through a furnace in the same direction, and discharging the ore with the manganese in the manganous condition.

7. The method of treating a manganese silver ore which comprises passing ore sulphur-containing material and air through a furnace in the same direction, converting the manganese to the manganous condition1 and discharging the ore with the silver as a sulphide.

8. The method of treating a manganese silver ore which comprises passing the ore through a furnace in contact with sulphurcontaining material an oxidizing reagent, converting the manganese tothe mangamuls condition, and discharging the ore with the silver as a sulphide.

9. The method of treating a manganese silver ore which comprises adding a sulphur containing substance to the ore, passing the mass and air through a furnace, converting the manganese to a manganous condition,

discharging the treated mass with the silver as a sulphide, and subjecting the mass to a leaching operation.

10. The method of treating a manganese silver ore which comprises adding a sulphur containing substance to the orc, passing the mass and air through a furnace, forming manganese sulphate, and discharging the mass with the silver as a sulphide.

11. The method of treating a manganese silver ore which comprises adding a sulphur' containing substance to the ore, passing the mass and air in the same direction through a furnace` forming manganese sulphate, dis charging the mass with the silver as a sulphide, and leaching out the manganese sulphate.

12. The method of treating a manganese silver ore sulphur-containing material, which comprises passing the ore and air through a furnace, converting the manganese to the manganous condition, anddischarging the treated mass with silver as a sulphur containing compound.

13. The method of treating a. manganese silver ore, which comprises passing the .ore sulphur-containing material and air through a furnace, converting the manganese to the manganous condition` discharging the mass from the furnace, extracting soluble matter with dilute sulphuric acid, recovering metallic values from the solution, and treating the residue with a silver extracting reagent.

v14:. The' method of treating a manganese silver ore which comprises passing ore sulphur-containing material and air through a furnace in the same direction, reducing manganese compounds to a low state of oxida tion, discharging the treated ore, extracting soluble compounds with aqueous reagents, and recovermg meta] compounds from the aqueous solution. 15. The method of treating a manganese silver ore which comprises adding a sulphur-containingsubstance tothe ore, passing the mass and air through a furnace in the same direction, converting' the manganese to the manganous condition, discharging the mass from the furnace, extracting soluble matter with dilute sulphuric acid, and Atreating the residue with a solvent for silver sulphide. l

In testimony whereof We affix our signatures.

MELVILLE F. COOLBAUGH. JOHN BURNS READ. 

